KR100243138B1 - An optical pickup device - Google Patents

Abstract

A light source for generating and outputting light, an objective lens for focusing incident light such that a light spot is formed on the recording surface of the disk, and first light path converting means arranged on an optical path between the light source and the objective lens to convert the advancing path of the incident light And second optical path converting means arranged on one side of the first optical path converting means and for branching the light passing through the objective lens and the first optical path converting means into the first and second light, and the second optical path converting means. A first photodetector having four light-receiving areas A, B, C, and D arranged side by side to receive and receive photoelectric conversion independently from each other; and a second optical path conversion. A second photodetector having four light-receiving regions E, F, G, and H arranged side by side to receive and receive photoelectric conversion independently from each other by means; From the signal output from the photodetector, the track error signal including the offset is detected by the push-pull method. A second circuit part for outputting a signal for correcting a track error signal including an offset from a signal detected in at least two light receiving areas of the first circuit part and the first light detector and at least two light receiving areas of the second light detector; Disclosed is an optical pickup apparatus including a track error signal detection unit having a first differential unit for differentially outputting a signal output from the first and second circuit units to output a track error signal from which offsets are removed.

Description

Optical pickup device

The present invention relates to an optical pickup apparatus, and more particularly, to an optical pickup apparatus capable of reducing an offset of a track error signal generated by movement of an objective lens.

In general, an optical pickup device is employed in a compact disc player, a digital video disc player, a CD-ROM drive, a DVD-ROM drive, or the like to perform recording / reproduction of information in a non-contact manner.

1 is a view schematically showing an optical arrangement of a conventional optical pickup device.

Referring to the drawings, a conventional optical pickup apparatus includes a light source 1 for generating and outputting light, an objective lens 12 for converging incident light so that an optical spot is formed on the recording surface of the disk 19, and incident divergent light. A collimating lens 18 for converting into parallel light, a beam splitter 13 for transmitting and / or reflecting incident light, and a photodetector 16 for detecting an error signal and an information signal.

The objective lens 12 is disposed between the light source 1 and the disk 19 to focus light incident from the light source 1 to form a light spot on the recording surface of the disk 19. At this time, the objective lens 12 is driven by an actuator (not shown) so that the optical spot formed by the objective lens 12 at the time of recording / reproducing the information signal can follow the correct track position of the disk 19. .

The beam splitter 13 reflects the light incident from the light source 1 toward the disk 19, and transmits the light incident from the objective lens 12 toward the photodetector 16. .

The collimating lens 13 is disposed between the objective lens 12 and the beam splitter 13 to convert the divergent light incident from the light source 1 into parallel light so as to be incident on the objective lens 12.

As illustrated in FIG. 2, the photodetector 16 includes two light receiving regions A and B each independently photoelectrically converting.

In such an optical pickup device, the light spots formed on the disk 19 by the objective lens 12 are reflected by the disk 19. At this time, the reflected light is different from the 0th order diffracted light by the track of the disk 19 according to the position from the center of each track of the disk 19. ± 1 The differential diffracted light is interfered and detected by the photodetector 16 via the objective lens 12 and the beam splitter 13.

Therefore, as shown in the figure, by differentially detecting the detection signals of the light receiving area A and the light receiving area B with the differential amplifier 15, the track error signal can be detected by the push-pull method.

On the other hand, such a disk 19 has an eccentricity of a predetermined size at the time of manufacture. Therefore, the objective lens 12 is provided to be moved within a predetermined range so that the above optical pickup apparatus can follow the correct track position when recording and reproducing the information signal.

Therefore, an offset is generated in the track error signal by the push-pull method of the photodetector 16 as described above, which makes it difficult to follow the correct track position of the disk 19.

In addition, in order to solve the offset problem of the track error signal by the push-pull method as described above, the incident light between the light source 1 and the beam splitter 13 is converted into zero order diffracted light, ± 1 A grating which branches into differential diffraction light or the like is further provided, and when the track error signal is detected by the three-beam method, the use efficiency of light for recording / reproducing the information signal is reduced. Therefore, the optical pickup device having such a structure is difficult to be employed in DVD_RAM or the like which requires a large light intensity.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical pickup apparatus capable of detecting a track error signal having a reduced offset and having high light utilization efficiency.

1 is a view schematically showing an optical arrangement of a conventional optical pickup device;

2 is a view schematically showing an example of the track error signal detection principle of FIG. 1;

3 is a view schematically showing an optical arrangement of an optical pickup apparatus according to a first embodiment of the present invention;

4 is a schematic view of the photodetector and track error signal detector of FIG. 3;

FIG. 5 is a graph for explaining a process of detecting a track error signal from which an offset is removed from the track error signal detector of FIG. 3; FIG.

6 is a view schematically showing another example of the track error signal detection unit of FIG. 4;

7 is a schematic view of a photodetector according to a second embodiment of the present invention employed in the optical pickup apparatus of FIG. 3;

8 is a view schematically showing an optical arrangement of an optical pickup apparatus according to a third embodiment of the present invention;

FIG. 9 is a schematic view of the photodetector and track error signal detector of FIG. 8; FIG.

<Explanation of symbols for main parts of drawing>

50 ... light source 51 ... first light path converting means

55 ... Objective lens 57 ... Astigmatism lens

59 ... disc 60 ... second optical path changing means

60a ... reflective surface 60b ... reflective surface

71,75 ... first and second photodetectors 77,100 ... photodetectors

80,110 ... track error signal detector 81,120 ... first circuit

83,121 ... 1st summer 85, 123 ... 2nd summer

87,125 ... 2nd differential part 91,130 ... 2nd circuit part

93.1st differential amplifier 94 ... 2nd differential amplifier

95 3rd differential 97,137 Filter unit

99,140 ... First Primary

In order to achieve the above object, an optical pickup apparatus according to the present invention comprises a light source for generating and emitting light; An objective lens for focusing incident light such that a light spot is formed on the recording surface of the disk; First optical path converting means disposed on an optical path between the light source and the objective lens to convert an advancing path of incident light; Second optical path converting means disposed on one side of the first optical path converting means and for branching the light passing through the objective lens and the first optical path converting means into first and second light; A first photodetector having four light-receiving regions A, B, C, and D arranged side by side to receive the first light via the second light path converting means and independently photoelectrically convert it; Wow; A second photodetector having four light-receiving regions (E) (F) (G) and (H) arranged side by side to receive the second light via the second light path converting means and independently photoelectrically convert it; Wow; A first circuit unit for detecting a track error signal including an offset by a push-pull method from the signals output from the first and second photodetectors, at least two light receiving regions of the first photodetector and the second photodetector A second circuit portion for outputting a signal for correcting a track error signal including an offset from a signal detected in at least two light receiving regions, and a track error in which the offset is removed by differentially outputting signals output from the first and second circuit portions. And a track error signal detection unit having a first differential unit for outputting a signal.

In addition, an optical pickup apparatus according to another aspect of the present invention, the light source for generating and emitting light; An objective lens for focusing incident light such that a light spot is formed on the recording surface of the disk; Optical path converting means disposed on an optical path between the light source and the objective lens and converting a traveling path of incident light; A photodetector having four light-receiving regions (A) (B) (C) (D) arranged side by side to receive light through the objective lens and the optical path converting means and independently photoelectrically convert; A first circuit portion for detecting a track error signal including an offset by a push-pull method from a signal output from the photodetector, and from a signal detected in the light receiving area (A) (D) or the light receiving area (B) (C) And a second circuit unit for outputting a signal for correcting a track error signal including an offset, and a first differential unit for outputting a track error signal from which offsets are removed by differentially outputting signals output from the first and second circuit units. And a track error signal detector.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view schematically showing an optical arrangement of an optical pickup apparatus according to a first embodiment of the present invention.

Referring to the drawings, the optical pickup apparatus according to the present invention includes a light source 50 for generating and emitting light, an objective lens 55 for focusing incident light to form an optical spot on the recording surface of the disk 59, and advancing incident light. First and second optical path changing means (51) (60) for converting a path, first and second photodetectors (71) (75) for receiving incident light, and track error signals of the disc (59). And a track error signal detector 80 for detecting.

The light source 50 includes a surface light laser or an edge emitting laser that emits light in the stacking direction of the semiconductor material layer.

The objective lens 55 is disposed between the light source 50 and the disk 59 to focus light incident from the light source 50 so as to form a light spot on the recording surface of the disk 59.

The first optical path converting means 51 is disposed on the optical path between the light source 50 and the objective lens 55. It is preferable to include a beam splitter so that most of the light incident from the light source 50 toward the first light path converting means 51 passes straight through and most of the light incident from the objective lens 55 reflects.

Here, it is also possible to include a polarizing beam splitter (not shown) which transmits or reflects incident light to the first optical path converting means 51 according to its polarization state. When the polarizing beam splitter is provided as described above, a quarter wave plate (not shown) for changing the polarization of incident light is further provided on the optical path between the polarizing beam splitter and the disk 59.

On the other hand, on the optical path between the light source 50 and the objective lens 55, it is preferable to further include a collimating lens 53 for converting the divergent light incident from the light source 50 side into parallel light. 3 shows an example in which the collimating lens 53 is disposed between the first optical path converting means 51 and the objective lens 55.

The second light path converting means 60 is preferably a beam splitter including a transflective surface 60a and a reflective surface 60b disposed adjacent to the transflective surface 60a. Here, the reflective surfaces 60b are arranged side by side with a predetermined interval spaced apart from the transflective surface 60a.

The transflective surface 60a reflects a part of the light reflected by the first light path converting means 51 to the reflecting surface 60b, and transmits the other light to the second photodetector ( 75). The reflective surface 60b reflects the first light reflected from the transflective surface 60a to face the first photodetector 71.

At this time, the light reflected from the disk 59 and incident to the second light path converting means 60 is focused light. Therefore, if the distance between the transflective surface 60a and the reflecting surface 60b and the arrangement of the first and second photodetectors 71 and 75 are appropriate, the objective lens 55 and the disk 59 When the distance between them is in the on-focus state, light of the same size is formed on the first and second photodetectors 71 and 75.

That is, in the on-focus state, the focused light is received by the second photodetector 75, and the first photodetector 71 has a diameter approximately equal to that of the light received by the second photodetector 75. Emitted light is received. In this case, the first light reflected by the transflective surface 60a and incident on the first photodetector 71 becomes light passing through the focal position f. Then, the second light transmitted through the transflective surface 60a and incident on the second photodetector 71 becomes light that has not passed the focal position.

Here, the second light path converting means 60 may be a beam splitter having a mirror surface to reflect and transmit the incident light at approximately the same predetermined light quantity ratio to branch into the first and second light. In this case, the first and second photodetectors 71 and 75 are arranged such that the diameter of the received light is approximately equal.

As shown in FIG. 4, the first photodetector 71 has four light receiving regions A, B, C, and D arranged side by side, and the light receiving regions A, B are shown in FIG. (C) (D) receives the first light via the second light path converting means 60 and photoelectrically converts the light independently.

Like the first photodetector 71, the second photodetector 75 includes four light receiving regions E, F, G, and H arranged side by side, and the light receiving region E (F) (G) (H) receives the second light via the second light path converting means 60 and photoelectrically converts them independently.

Here, the first and second photodetectors 71 and 75 are arranged in a line on the exit surface of the second optical path converting means 60, as shown in FIG. The two photodetectors 71 and 75 may be integrally provided on the same substrate.

On the other hand, the light received by the first and second photodetectors 71 and 75 is different from the 0th order diffracted light according to the position from the center of each track of the disk 59. ± First order diffracted light is interference and reflected light. Therefore, the received light has a zeroth order diffracted light region (not a hatched region) and the zeroth order diffracted light ± It consists of an interference area (hatched area) of primary diffracted light.

The track error signal detector 80 detects a track error signal of the disc 59 from the output signals of the first and second photodetectors 71 and 75.

The track error signal detection unit 80 includes a first circuit unit 81 for detecting a track error signal with an offset by a push-pull method, and a second circuit unit 91 for outputting a signal for correcting a track error signal with an offset. And a first differential unit 99 for outputting a track error signal from which the offset is removed.

The first circuit unit 81 detects a track error signal including an offset by a push-pull method from detection signals of the respective light receiving regions of the first and second photodetectors 71 and 75. To this end, the first circuit unit 81 is a second differential unit that differentials the output signals of the first and second summers 83 and 85 and the first and second summers 83 and 85. (87).

The first summer 83 obtains a sum signal of symmetric light receiving regions corresponding to half of the first and second photodetectors 71 and 75. That is, the first adding unit 83 is a summer 83a for summing detection signals of the light receiving area A and the light receiving area B, and detection signals of the light receiving area G and the light receiving area H. A summer 83b for summing and a summer 83c for summing output signals of the two summers 83a and 83b. Therefore, the first adding unit 83 sums and outputs detection signals of the light receiving area A, the light receiving area B, the light receiving area G, and the light receiving area H.

The second adding unit 85 obtains a sum signal of the remaining light receiving areas detected by the first adding unit 83 among the light receiving areas of the first and second photodetectors 71 and 75. That is, the second adding unit 85 includes an adder 85a for summing detection signals of the light receiving area C and the light receiving area D, and detection signals of the light receiving area E and the light receiving area F. A summer 85b for summing and a summer 85c for summing output signals of the two summers 85a and 85b. Therefore, the second adding unit 85 sums and outputs detection signals of the light receiving area C, the light receiving area D, the light receiving area E, and the light receiving area F.

The second differential unit 87 differentially outputs the output signals of the first adding unit 83 and the second adding unit 85, and includes a track error signal including an offset by a push-pull method. α ).

Therefore, the track error signal including the offset output from the second differential unit 87 ( α ) May be expressed as in Equation 1. Here, the symbols representing the light receiving regions and their detection signals are the same for convenience.

α = (A + B-C-D)-(E + F-G-H)

As such, the track error signal including the offset by the push pull method output from the second differential unit 87 ( α ) Is shown as shown in FIG. 5 as the objective lens 55 moves. This track error signal ( α As shown in the figure, as the amount of movement of the objective lens 55 increases, the track error signal ( α ) Has an offset in which the center potential increases.

Here, the x axis represents the objective lens shift amount (mm), and the y axis represents the detection signal at a predetermined stage of the track error signal detection unit 80.

The second circuit unit 91 may include the track error signal ( α Outputs a signal for correcting the offset included in. To this end, as illustrated in FIG. 4, the second circuit unit 91 includes a first differential amplifier 93 for differentially amplifying detection signals of the light receiving region A and the light receiving region D, and the light receiving region ( E) and a second differential amplifier 94 for differentially amplifying detection signals in the light receiving region H, and a third differential amplifier for differentially outputting the output signals of the first and second differential amplifiers 93 and 94. FIG. And a filter unit 97 for filtering the output signal of the third differential unit 95 and outputting an offset correction signal. At this time, the output signal of the third differential unit 95 ( t ₁ ) Can be expressed as in Equation 2.

t ₁ = (AD-E + H)

This output signal t ₁ Denotes a track error signal (1) of the first circuit unit 81 as the objective lens 55 moves. α Like), it is an AC signal.

The filter unit 97 outputs an output signal of the third differential unit 95. t ₁ Low pass filter for filtering low pass) or the output signal ( t ₁ ) May be formed of a high frequency elimination filter that blocks high frequency components.

Therefore, the output signal of the third differential unit 95 ( t ₁ Is passed through the filter section 97, the output signal ( t ₁ ) Is the DC signal ( t ₂ ) And this DC signal ( t ₂ ) Can be expressed as in Equation 3. Equation 3 shows an example in which output signals of the first and second differential amplifiers 93 and 94 are low pass filtered (LPF).

t ₂ = LPF (AD)-LPF (EH)

At this time, the DC signal ( t ₂ That is, the offset correction signal ( t ₂ ) Changes in accordance with the movement of the objective lens 55 (shown in dashed lines in FIG. 5).

On the other hand, the DC signal ( t ₂ Is the track error signal ( α Since the center potential of) does not coincide with the increasing offset, the direct current signal ( t ₂ ) Can be removed as follows.

That is, in the first differential amplifier 93, detection signals of the light receiving region A and the light receiving region D are obtained by a predetermined gain ( G ₁ Differential amplification, and the second differential amplification unit 94 obtains a predetermined gain (a) of the detection signals of the light receiving region E and the light receiving region H. G ₂ Differentially amplifies the DC signal through the third differential unit 95 and the filter unit 97; β ) Is the same as Equation 4.

β = G1 * LPF (A-D)-G2 * LPF (E-H)

At this time, the DC signal ( β ) Changes as shown in FIG. 5 as the objective lens 55 moves.

The DC signal ( β That is, the offset correction signal ( β ) Gain G ₁ and G ₂ When properly adjusted, offset correction signal ( t ₂ (Indicated by dashed lines) is changed, and as shown in FIG. 5, the track error signal ( α ) Will match the offset contained in).

Therefore, the track error signal by the push-pull method as described above in the first differential portion 99 α ) And the correction signal ( β ), The track error signal (detected by the first circuit unit 81) α The offset included in) is removed.

Therefore, the track error signal TES according to the present invention from which the offset is removed can be represented by Equation 5.

TES = (A + B-C-D)-(E + F-G-H)-G1 * LPF (A-D) + G2 * LPF (E-H)

The track error signal TES is changed as shown in FIG. 5 in accordance with the movement of the objective lens 55.

Here, the correction signal ( β As shown in FIG. 6, the light receiving area (B) and the light receiving area (C), the light receiving area (F) and the light receiving area (G) may be obtained in the same manner as described above. It may represent an error signal TES.

Although the detailed description is omitted, the information signal of the disk 59 is not equal to the detection signal of each of the light receiving areas A, B, C, D, E, F, G, and H. The sum signal is detected as A + B + C + D + E + F + G + H.

On the other hand, in the optical pickup device provided as described above, when the distance between the objective lens 55 and the disk 59 is in the in-focus state, the first and second photodetectors 71 and 75 are formed. The light spots are the same size. When the distance between the objective lens 55 and the disk 59 is in the off focus state, the size of the light spot formed on the first and second photodetectors 71 and 75 is changed. Therefore, the focus error signal FES can be detected by the beam size method, and the focus error signal FES by the beam size method can be expressed as shown in equation (6).

FES = (A + D-B-C)-(E + H-F-G)

In this case, the focus error signal FES becomes 0 in the on focus state and has a value other than 0 in the off focus state.

FIG. 7 is a view schematically illustrating a light detector 77 according to a second embodiment of the present invention employed in the optical pickup apparatus of FIG. 3. In this embodiment, one of the first and second photodetectors 71 and 75 of FIG. 4 is used to detect the focus error signal by astigmatism, as shown in FIG. 7. This feature is also provided.

That is, for example, two light receiving regions, which are symmetrical from the center of the photodetector 77, are divided in two. In addition, it is preferable to further include an astigmatism lens (not shown) for generating astigmatism on the optical path between the first and second optical path conversion means (51, 60).

In this case, the focus error signal is a light receiving area ( b ₁ ) And light receiving area ( c ₂ ) And the light receiving area ( b ₂ ) And light receiving area ( c ₁ Is detected by differentially adding up the sum signal.

Here, the photodetector 77 is 2 × 4 It is also possible to have eight light-receiving areas divided into matrix arrangements.

8 is a view schematically showing an optical arrangement of an optical pickup apparatus according to a third embodiment of the present invention.

Referring to the drawings, an optical pickup apparatus according to the present invention includes a light source 50, an objective lens 55, an optical path converting means 51, a photodetector 100 for receiving incident light, and a photodetector ( And a track error signal detection unit 110 for detecting a track error signal of the disc 59 from the signal output from 100. Here, the same reference numerals as those in FIG. 3 have the same structure and function, and thus detailed description thereof will be omitted.

The photodetector 100 receives the light passing through the objective lens 55 and the optical path converting means 51 and each of four light receiving regions A and B arranged side by side to independently photoelectrically convert ( It is preferable to provide C) (D).

It is preferable that at least two light receiving regions symmetrical from the center of the light receiving regions A, B, C, and D are divided into two. 9 shows that each of the light receiving regions B and C has two light receiving regions ( b ₁ , b ₂ ) ( c ₁ , c ₂ Shows an example divided into two parts. On the other hand, the photodetector 100 2 × 4 It is also possible to comprise eight light-receiving areas which are dividedly arranged to have a matrix arrangement.

The track error signal detector 110 detects a track error signal of the disc 59 from the signal output from the photodetector 100.

The track error signal detection unit 110 includes a first circuit unit 120 for detecting a track error signal including an offset by a push-pull method, and a second circuit unit 130 for outputting a signal for correcting a track error signal including an offset. ) And a first differential part 140 that differentials signals output from the first and second circuit parts 120 and 130.

The first circuit unit 120 includes a first summing unit 121 for summing detection signals of the light receiving area A and the light receiving area B, and detection signals of the light receiving area C and the light receiving area D. Track error signal including an offset by differentially outputting the second summation unit 123 for summation and the output signals of the first and second summation units 121 and 123. α ) Is made up of a second differential part 125.

Here, the detection signal of the light receiving area (B) is, as shown, the light receiving area ( b ₁ Detection signal and light receiving area b ₂ Is the sum signal of the detected signals. The detection signal of the light receiving area C is a light receiving area ( c ₁ Detection signal and light receiving area c ₂ Is the sum signal of the detected signals.

Meanwhile, the track error signal including the offset detected by the push pull method ( α ) May be expressed as in Equation 7. Here, the symbols representing the light receiving regions and their detection signals are the same for convenience.

tes1 = (A + B-C-D)

= {A + ( b ₁ + b ₂ )-( c ₁ + c ₂ ) -D}

At this time, the track error signal ( α ) Is the track error signal of FIG. 5 according to the first embodiment of the present invention. α ), And the center potential thereof increases as the amount of movement of the objective lens 55 increases.

The second circuit unit 130 is the track error signal ( α Outputs a signal for correcting the offset included in. To this end, the second circuit unit 91 includes a differential amplifier 131 and a filter unit 137.

The differential amplifier 131 receives a detection signal of the light receiving area A and the light receiving area D by a predetermined gain ( G ₁ Differentially amplify

The filter unit 137 filters the output signal of the differential amplifier 131. Here, since the filter unit 137 has the same structure and function as the filter unit 97 according to the first embodiment of the present invention described with reference to FIG. 4, a detailed description thereof will be omitted.

The output signal of the second circuit unit 130 as described above is a direct current signal ( β ) Can be expressed as Equation (8).

β = G1 * LPF (A-D)

This DC signal ( β That is, the offset correction signal ( β Benefit of G ₁ If properly adjusted, the offset correction signal (Fig. 5) according to the first embodiment of the present invention β Like the track error signal α Correction signal corresponding to the offset at which the center potential of β ) Can be obtained.

Therefore, the track error signal by the push pull method as described above in the first differential unit 140 ( α ) And the correction signal ( β ), The track error signal of the output signal of the first circuit unit 120, as in the first embodiment of the present invention, α ) Offset is removed.

Therefore, the track error signal TES according to the present embodiment in which the offset is removed may be represented by Equation 9.

TES = (A + B-C-D)-G1 * LPF (A-D)

The track error signal TES is changed as shown in FIG. 5 in accordance with the movement of the objective lens 55 as in the first embodiment of the present invention.

Here, the differential amplifier 131 receives the detection signals of the light receiving region B and the light receiving region C with a predetermined gain ( G ₁ It can be arranged to differentially amplify). The track error signal TES may be detected correspondingly.

The information signal of the disk 59 can be detected by summing the detection signals of the respective light receiving regions of the photodetector 100.

Meanwhile, an astigmatism lens 59 may be further provided on the optical path between the optical path converting means 51 and the photodetector 100 so as to detect the focus error signal by the astigmatism method. At this time, the focus error signal is the light receiving area ( b ₁ ) And light receiving area ( c2 ) And the light receiving area ( b ₂ ) And light receiving area ( c ₁ ) By detecting the differential signal.

The optical pickup apparatus according to the present invention as described above can remove the offset of the track error signal due to the movement of the objective lens by using the signal detected by the second circuit unit, and can follow the correct track position of the disc. Therefore, the information signal of the disc can be recorded / reproduced accurately.

In addition, since the light received by the photodetector according to the present invention is used when recording / reproducing the information signal, the light utilization efficiency is high.

Claims (17)

A light source for generating and emitting light; An objective lens for focusing incident light such that a light spot is formed on the recording surface of the disk; First optical path converting means disposed on an optical path between the light source and the objective lens to convert an advancing path of incident light; Second optical path converting means disposed on one side of the first optical path converting means and for branching the light passing through the objective lens and the first optical path converting means into first and second light; A first photodetector having four light-receiving regions A, B, C, and D arranged side by side to receive the first light via the second light path converting means and independently photoelectrically convert it; Wow; A second photodetector having four light-receiving regions (E) (F) (G) and (H) arranged side by side to receive the second light via the second light path converting means and independently photoelectrically convert it; Wow; A first circuit unit for detecting a track error signal including an offset by a push-pull method from the signals output from the first and second photodetectors, at least two light receiving regions of the first photodetector and the second photodetector A second circuit portion for outputting a signal for correcting a track error signal including an offset from a signal detected in at least two light receiving regions, and a track error in which the offset is removed by differentially outputting signals output from the first and second circuit portions. And a track error signal detection unit having a first differential unit for outputting a signal. The method of claim 1, wherein the first circuit portion, A first summing unit for summing detection signals of the light receiving area (A), the light receiving area (B), the light receiving area (G) and the light receiving area (H); A second summing unit for summing detection signals of the light receiving area (C), the light receiving area (D), the light receiving area (E), and the light receiving area (F); And a second differential unit configured to differentially output signals of the first and second adders and detect a track error signal including an offset by a push-pull method. The method of claim 1, wherein the second circuit portion, The detection signal of the light receiving area A and the light receiving area D is G ₁ A first differential amplifier which differentially amplifies the amplifier; The detection signal of the light receiving area E and the light receiving area H is G ₂ A second differential amplifier for differential amplification; A second differential unit which differentials the output signals of the first and second differential amplifiers; And a filter unit for filtering an output signal of the second differential unit and outputting an offset correction signal. The method of claim 1, wherein the second circuit portion, The detection signals of the light receiving area B and the light receiving area C are G ₁ A first differential amplifier which differentially amplifies the amplifier; The detection signals of the light receiving area F and the light receiving area G G ₂ A second differential amplifier for differential amplification; A second differential unit which differentials the output signals of the first and second differential amplifiers; And a filter unit for filtering an output signal of the second differential unit and outputting an offset correction signal. The optical pickup apparatus of claim 3 or 4, wherein the filter unit comprises a low pass filter for low pass filtering the output signal of the second differential unit. The optical pickup apparatus of claim 3 or 4, wherein the filter unit comprises a high frequency elimination filter that blocks high frequency components of an output signal of the second differential unit. The method of claim 1, wherein the second optical path conversion means, A transflective surface for transmitting part of the light incident from the first light path converting means and reflecting the rest of the light; And a reflection surface disposed adjacent to the first transflective surface to reflect light reflected from the first transflective surface. 8. The light detector of claim 7, wherein the first and second photodetectors receive focused light at the second photodetector when the distance between the objective lens and the disk is in focus. An optical pickup apparatus, wherein the divergent light having a diameter substantially equal to the light received by the two photodetectors is received. The optical pickup apparatus of claim 1, wherein at least two light receiving regions that are symmetrical from the center of the first or second photodetector are divided in two. A light source for generating and emitting light; An objective lens for focusing incident light such that a light spot is formed on the recording surface of the disk; Optical path converting means disposed on an optical path between the light source and the objective lens and converting a traveling path of incident light; A photodetector having four light-receiving regions (A) (B) (C) (D) arranged side by side to receive light through the objective lens and the optical path converting means and independently photoelectrically convert; A first circuit portion for detecting a track error signal including an offset by a push-pull method from a signal output from the photodetector, and from a signal detected in the light receiving area (A) (D) or the light receiving area (B) (C) And a second circuit part for outputting a signal for correcting a track error signal including an offset, and a first differential part for outputting a track error signal from which offset is removed by differentially outputting signals output from the first and second circuit parts. And a track error signal detection unit. The method of claim 10, wherein the first circuit portion, A first summing unit for summing detection signals of the light receiving area (A) and the light receiving area (B); A second adding unit for adding up the detection signals of the light receiving area (C) and the light receiving area (D); And a second differential unit configured to differentially output signals of the first and second adders and detect a track error signal including an offset by a push-pull method. The method of claim 10, wherein the second circuit portion, A differential amplifier for differentially amplifying the detection signals in the light receiving area (A) and the light receiving area (D) with a predetermined gain (G1); And a filter unit for filtering the output signal of the differential amplifier and outputting an offset correction signal. The method of claim 10, wherein the second circuit portion, A differential amplifier for differentially amplifying the detection signals of the light receiving region (B) and the light receiving region (C) with a predetermined gain (G1); And a filter unit for filtering the output signal of the differential amplifier and outputting an offset correction signal. The optical pickup apparatus of claim 12 or 13, wherein the filter unit comprises a low pass filter for low pass filtering the output signal of the differential amplifier. The optical pickup apparatus of claim 12 or 13, wherein the filter unit comprises a high frequency elimination filter that blocks high frequency components of an output signal of the differential driving amplifier. The optical pickup apparatus of claim 10, further comprising an astigmatism lens for generating astigmatism on an optical path between the optical path converting means and the photodetector. 17. The light receiving area of claim 16, wherein each of the light receiving areas (B) and (C) has two light receiving areas ( b ₁ , b ₂ ) ( c ₁ , c2 Is divided into two, and the light receiving area ( b ₁ ) And light receiving area ( c2 ) And the light receiving area ( b ₂ ) And light receiving area ( c ₁ Optical signal pickup device for detecting a focus error signal by astigmatism method by differentially sum of the sum signal.

Images